Modularized conveyor belts and accompanying drive systems are well known in the art, and are found with modules of various characteristics that are coupled together and articulated by means of pivot rods so that they can be endlessly moved by means of rotatable sprockets. The trend in the art is to produce modules of various shapes and interactions for achieving various advantages in operation. It is a general problem in the art to provide modular elements that are easily made, such as by molding from plastic, and yet present superior operating characteristics particularly in the critical sprocket and module driving surface interface. Thus, one objective of this invention is to provide improved simplified modular elements and conveyor belt drive systems embodying modular elements.
A critical operational region in conveyor belt systems driven by a sprocket at the hinged joints is caused by the hinging driving interface between the belt modules and the relatively moving rotating sprocket drive surfaces. The prior art has many different configurations of sprocket and belt structure with special driving surface features. However, the prior art hinge region drive surfaces present operational disadvantages. In consideration of the driving interface design of prior art conveyor belt systems, some of the critical operating conditions involved are the wear at interfacing drive surfaces, the ability of the belt to articulate smoothly over small diameter sprockets, the performance of the belt over the range of no-load to full-load conditions, the energy or friction losses of the drive system, the ability to run at various speeds, freedom from vibration and noise, and the ease of replacing worn surfaces or parts. In particular the interface between sprocket and module surfaces generally react during the hinging acting to urge the belt away from the sprocket to introduce significant problems in controlling belt slack and tension and wear at the sprocket-hinge interface surfaces. No known prior art belt system has been completely satisfactory over such a comprehensive range of desiderata. Thus, it is a further objective of this invention to provide improved belt drive systems advantageous with respect to these foregoing requirements, which is useful for a variety of belt module configurations.
The significant uncorrected problem that has surfaced in many of the prior art sprocket to belt drive interface systems is that the motion of the sprocket and the interaction of the drive surfaces tend to generate forces which drive the belt away from the sprocket. This visibly reacts in a manner similar to slack in the unloaded system, and if the belt is tightened to remove slack, then the operating friction becomes excessive, without correcting the urging forces, thereby causing inefficient operation with more wear on the drive surfaces. Other attempted solutions, such as counteracting forces applied to the belt or limiting guide brackets to limit belt movement away from the sprocket are not satisfactory solutions. Accordingly a still further objective of this invention is to provide an improved conveyor belt system wherein interacting belt-sprocket drive forces that tend to drive the belt away from the sprocket are avoided.
Other objects, features and advantages of the invention will become apparent from the following description taken with the accompanying drawings and claims.